The following initargs are geometry hints, influencing the initial size and position of an element and constraining its size:

:x

The
x
position of the element in a pinboard.

:y

The
y
position of the element in a pinboard.

:external-min-width

The minimum width of the element in its parent.

:external-min-height

The minimum height of the element in its parent.

:external-max-width

The maximum width of the element in its parent.

:external-max-height

The maximum height of the element in its parent.

:visible-min-width

The minimum visible width of the element.

:visible-min-height

The minimum visible height of the element.

:visible-max-width

The maximum visible width of the element.

:visible-max-height

The maximum height of the element.

:internal-min-width

The minimum width of the display region.

:internal-min-height

The minimum height of the display region.

:internal-max-width

The maximum width of the display region.

:internal-max-height

The maximum height of the display region.

Accessors

element-parent

Readers

element-interfacehelp-key

Description

The class
element
contains the slots
parent
and
interface
which contain the element and the interface that the element is contained in respectively. The writer method
element-parent
can be used to re-parent an element into another parent (or to remove it from a container entirely by setting its parent to
nil
). Note that an element should not be used in more than one place at a time.

The initarg
accepts-focus-p
specifies that the element can accept input. The default value is
t
. In some subclasses including display-pane and title-pane the default value of
accepts-focus-p
is
nil
. A pane accepts the input focus if and only if the function accepts-focus-p returns true.

accepts-focus-p
also influences whether a pane is a tabstop on Windows, where a pane acts as a tabstop if and only if the function accepts-focus-p returns true and the
:accepts-focus-p
initarg value is
:force
. On Motif and Cocoa, a pane acts as a tabstop if and only if the function accepts-focus-p returns true.

help-key
is used to determine how help is displayed for the pane. The value
nil
means that no help is displayed. Otherwise,
help-key
is passed to the
interface-help-callback
, except when
help-key
is
t
, when the name of the pane is passed to the
interface-help-callback
. For details of
interface-help-callback
, see interface.

All elements accept initargs (listed above) representing hints as to the initial size and position of the element. By default elements have a minimum pixel size of one by one, and a maximum size of
nil
(meaning no maximum), but the hints can be specified to change these values. The possible values for these hints are as follows:

integer

The size in pixels.

t

For
:visible-max-width
,
t
means use the value of
:visible-min-width
.

For
:visible-max-height
,
t
means use the value of
:visible-min-height
.

:text-width

The width of any text in the element.

:text-height

The height of any text in the element.

:screen-width

The width of the screen.

:screen-height

The height of the screen.

Also, hints can be a list starting with any of the following operators, followed by one or more hints.

max

The maximum size of the hints.

min

The minimum size of the hints.

+

The sum of the hints.

-

The subtraction of hints from the first.

*

The multiplication of the hints.

/

The division of hints from the first.

Also, a hint can be a two element list specifying the size of a certain amount of text when drawn in the element:

(:character
integer
)

(character
integer
)

The size of
integer
characters.

(:string
string
)

(string
string
)

The size of
string
.

A hint can be a two-element list interpreted as the value of a symbol:

(symbol-value
foo
)

The size of the
symbol-value
of
foo
.

Finally, you can choose to
apply
or
funcall
an arbitrary function, by passing a list starting with
funcall
or
apply
, followed by the function and then the arguments.

The hints of an element can be changed dynamically using set-hint-table: such a call might change the geometry.

Note: If the
visible-max-width
is the same as the
visible-min-width
, then the element is not horizontally resizable. If the
visible-max-height
is the same as the
visible-min-height
, then the element is not vertically resizable.

Note:
Some classes have default initargs providing useful hints. For example, display-pane has
:text-height
as the default value of
:visible-min-height
, ensuring that the text is visible.

Note: The
ratios
,
x-ratios
and
y-ratios
settings in some layouts (for example grid-layout) also control the actual size of the pane when the constraints are not specified. In particular, if
nil
is used in the ratios then the associated pane(s) will be fixed at their minimum size.

Compatibility Note

The
:min-width
,
:max-width
,
:min-height
, and
:max-height
initargs are still accepted for compatibility with LispWorks 3.2, but their use is discouraged.

In LispWorks 4,
:visible
-
min-width
means the same as
:min-width
, but takes precedence if both are specified. The use of
:min-width
can lead to confusion because some CAPI classes have default values for
:visible-min-width
which will override
:min-width
. Similarly for :
min-height
,
:max-width
, and
:max-height
. Therefore, your code should use
:visible-min-width
and friends.

Examples

(capi:display (make-instance 'capi:interface

:title "Test"

:visible-min-width 300))

(capi:display (make-instance 'capi:interface

:title "Test"

:visible-min-width 300

:visible-max-height 200))

Here is a simple example that demonstrates the use of the
element-parent
accessor to place elements.